Visual surveillance via cameras or closed circuit televisions systems is well known in the art as demonstrated by, for example, U.S. Pat. No. 5,216,502 (Katz). These systems have enabled visual records to be stored on videotape for later analysis. However, because of the amount of information recorded, it is difficult to review all the information and identify patterns, such as patterns of employee theft. Employee theft most often occurs at the point-of-sale, for example, at a cash register or at a bank teller's station. and can be identified by observing transactions that fall outside normal activity.
Current video surveillance systems typically record transaction activity with two types of transaction information: a video signal for visual information and digital data to reflect each transaction as it is entered into the point-of-sale device, such as a cash register or bank teller register. In the past, one method of storing this information has been to overlay the digital data on the video signal and record and store both types of information together as a mixed composite video signal. Representative of such systems are the surveillance systems disclosed in U.S. Pat. No. 4,120,004 (Coutta), U.S. Pat. No. 4,922,339 (Stout), and U.S. Pat. No. 4,991,008 (Nama). Wile this type of combined video record is not easily tampered with, the problem with this method is that there is a tremendous volume of information which must be manually reviewed in order to identify patterns of unwanted or criminal activity.
Another method for storing the visual and digital information has been to use the digital data as the leading information or header for the video signal as described in U.S. Pat. Nos. 4,237,483 and 4,145,715 (Clever patents). This merger of information, however, tends to degrade the quality of the video image and still requires that an operator scan all the information in its entirety to identify problem areas. Use of these system with a plurality of cameras requires additional cabling installed in order to coordinate the operation of all cameras in sync with each other. In addition, because much of the digital information is stored separately from the video images, this information is vulnerable to tampering by dishonest store managers, for example.
A third and more recent method is to store the digital data in the audio portion of the video signal and to mark transactions of interest with an alarm signal in the audio track. One example of such a system is disclosed by U.S. Pat. No. 5,216,502 (Katz). This method reduces the amount of material an operator must scan by allowing the operator to move quickly to those portions of the videotape which are marked by the audio alarm. Nonetheless, this method requires that all transactions of interest be previously marked. If transactions of interest are not marked, the operator still must scan all the transaction to find the transaction of interest. In addition, this third method does not provide any easy way for an operator to identify patterns and trends outside of a relatively small group of preselected conditions which cause an alarm signal to be recorded.
One solution to the problem of viewing irrelevant information is to record only those transactions of interest such as is done by the System 500 or System 1000 sold by Video Controls Limited of 1 Aston Fields Road, Whitehouse Industrial, England or the Sensormatic Electronics Corporation POS/EM system sold by Sensormatic of Deerfield, Beach, Fla. The Video Controls system records user-defined events, such as void transactions, through its closed circuit TV and provides a summary videotape of particular events with the details of the cash register transaction superimposed over the videotape picture. One problem is that the system records only those events that the user predefines as important. Thus, critical transactions which are not of prior interest may be lost. For example, often events, such as void transactions, merely point to a larger pattern of theft. This pattern of theft often is evident only by viewing several entries or transactions prior to the void transaction.
The Sensormatic Electronics Corporation POS/EM system automatically aims a camera at the register once a pre-defined exception to normal cash register transactions is detected in the electronic cash register. The Sensormatics Electronics Corporation POS/EM system then displays the cash register transaction data on the video picture. The problem here is that, because the camera is triggered only after an exception is detected in the electronic cash register data, the camera may not record the actual event leading to the loss. Such a time delay, even a small one, may not record the key activity. Again, separate storage of the visual picture data and digital data opens the system to tampering.
In sum, a multimedia capture and audit system for a video surveillance network that captured all relevant information and stored that information in a tamper-resistant form and offered improved review and audit capabilities would be greatly appreciated.